1. Field of the Invention
The invention relates generally to signal generators and specifically to instruments capable of simulating the complex signals that a servowritten head disk assembly (HDA) would produce during seek and read operations.
2. Description of the Prior Art
Traditionally, development of hard disk drive electronics has been delayed until after two critical phases were completed. First, the manufacture of the disk drive electromechanical assembly, and second, the development of a corresponding servowriter. The drive housing with actuator, head and media all had to exist, and the servowriter had to be able to write the respective servo patterns, on the disk(s) before the servo electronics could be tested and debugged. Designers of servo-based floppy, optical and Winchester drives must wait to develop the servo electronics until the actual head disk drive mechanism is built. Later in production, drive electronics are conventionally tested by connecting up a test HDA, or by testing with the target drive mechanics. This method depends on an assumed "normalcy" of the particular HDA, which actually has its own unique characteristics that are not readily controllable.
An instrument is needed that will permit test and debug of the drive electronics with the initial servo system design, to avoid the four to six month wait normally required. Such an instrument should also be able to be used in a manufacturing process to test electronic circuit boards safely before mating them with a costly HDA. The simulator should be programmable to simulate various conditions, including worst-case mechanical characteristics, to test the tolerance electronics and its capability to recover. By testing the boards under worst case conditions, the electronics design and production process can be optimized to result in higher product quality, reliability and yields.